Ukrainian President Volodymyr Zelenskyy was making his way to Washington on Wednesday for a summit with President Joe Biden and to address Congress in his first known trip outside the country since Russia’s invasion began in February.

Zelenskyy said on his Twitter account that the visit was “to strengthen resilience and defense capabilities” of Ukraine and discuss cooperation between his country and the U.S with Biden.

The highly sensitive trip is taking place after 10 months of a brutal war that has seen tens of thousands killed and wounded on both sides of the conflict, along with devastation for Ukrainian civilians. It also comes as U.S. lawmakers are set to vote on a year-end spending package that includes about $45 billion in emergency assistance to Ukraine and as the Pentagon prepares to send Patriot surface-to-air missiles to the country to defend itself.

Zelenskyy headed abroad after making a daring and dangerous trip Tuesday to what he called the hottest spot on the 1,300-kilometer (800-mile) front line of the conflict, the city of Bakhmut in Ukraine’s contested Donetsk province. He praised Ukrainian troops for their “courage, resilience and strength” as artillery boomed in the background.

Poland’s private broadcaster TVN24 said Zelenskyy crossed into Poland early Wednesday on his way to the U.S. The station showed footage of what appeared to be Zelenskyy arriving at a train station and being escorted to a motorcade. TVN24 said the video, which was partially blurred for security reasons, was shot Wednesday morning in Przemysl, a Polish border town that has been the arrival point for many refugees fleeing the war.

White House press secretary Karine Jean-Pierre, in a statement Tuesday night, said that Biden looks forward to Zelenskyy’s visit and that the address to Congress will demonstrate “the strong, bipartisan support for Ukraine.”

“The visit will underscore the United States’ steadfast commitment to supporting Ukraine for as long as it takes, including through the provision of economic, humanitarian, and military assistance,” she said.

Zelenskyy was scheduled to meet with Biden at the White House in the afternoon and then join Biden for a news conference in the East Room. He was expected to address Congress in the evening.

House Speaker Nancy Pelosi, in her invitation to Zelenskyy to address a joint meeting of Congress at the U.S. Capitol, said that “The fight for Ukraine is the fight for democracy itself” and that lawmakers “look forward to hearing your inspiring message of unity, resilience and determination.”

U.S. and Ukrainian officials have made clear they don’t envision an imminent resolution to the war and are preparing for fighting to continue for some time. Biden has repeated that while the U.S. will arm and train Ukraine, American forces will not be directly engaged in the conflict.

Biden and Zelenskyy first discussed the idea of a visit to Washington during their most recent phone call, on Dec. 11, and a formal invitation followed three days later, said a senior U.S. administration official, briefing reporters on the condition of anonymity because of the sensitive nature of the visit. Zelenskyy accepted the invitation on Friday and it was confirmed on Sunday, when the White House began coordinating with Pelosi to arrange the congressional address.

The White House consulted with Zelenskyy on security for his departure from Ukraine and travel to Washington, including the risk of Russian action while Zelenskyy was briefly out of the country, the official added, declining to detail the measures taken to safeguard the Ukrainian leader. The official said the U.S. expected Russia to continue its attacks on Ukrainian forces and civilian infrastructure targets despite the trip.

The tranche of U.S. funding pending before Congress would be the biggest American infusion of assistance yet to Ukraine — even more than Biden’s $37 billion emergency request — and is meant to ensure that support flows to the war effort for months to come.

On Wednesday, the U.S. was also set to announce that it will send a major package of $1.8 billion in military aid to Ukraine that will for the first time include a Patriot missile battery and precision guided bombs for its fighter jets, U.S. officials said.

The aid signals an expansion by the U.S. in the kinds of advanced weaponry it will send to Ukraine to bolster its air defenses against what has been an increasing barrage of Russian missiles in recent weeks. The package will include about $1 billion in weapons from Pentagon stocks and $800 million in funding through the Ukraine Security Assistance Initiative, officials said.

The decision to send the Patriot battery comes despite threats from Russia’s Foreign Ministry that the delivery of the advanced surface-to-air missile system would be considered a provocative step and that the Patriot battery and any crews accompanying it would be a legitimate target for Moscow’s military.

It’s unclear when the Patriot battery would arrive on the front lines in Ukraine, since U.S. troops will have to train Ukrainian forces on how to use the high-tech system. The training could take several weeks and is expected to be done in Germany. To date, all training of Ukraine’s forces by the U.S. and its Western allies has taken place in European countries.

The visit comes at an important moment as the White House braces for greater resistance when Republicans take control of the House in January and give more scrutiny to aid for Ukraine. GOP leader Kevin McCarthy has said his party’s lawmakers will not write a “blank check” for Ukraine.

Biden and Zelenskyy frequently have talked by phone as the White House arranges new tranches of military assistance for Ukraine. The calls have been mostly warm, with Biden praising Ukraine for remaining steadfast against the Russians and Zelenskyy thanking the U.S. president for support.

The one exception was a June phone call soon after Biden notified Zelenskyy that an additional $1 billion package was headed to Ukraine. Zelenskyy didn’t miss a beat in ticking off the additional assistance he said Ukraine needed.

That irked Biden, who underscored to Zelenskyy the American people’s generosity. But the brief moment of tension hasn’t caused any lasting difficulty, according to officials familiar with the episode.

Pelosi, who visited Zelenskyy earlier this year in Kyiv, encouraged lawmakers to be on hand for Wednesday evening’s address by the Ukrainian leader.

“We are ending a very special session of the 117th Congress with legislation that makes progress for the American people as well as support for our Democracy,” Pelosi wrote Tuesday in a letter to colleagues. “Please be present for a very special focus on Democracy Wednesday night.”

Later at the Capitol she said of Ukrainians, “They are fighting for democracy for all of us.”

Russia’s invasion, which began Feb. 24, has lost momentum. The illegally annexed provinces of Donetsk, Kherson, Luhansk and Zaporizhzhia remain fiercely contested.

With the fighting in the east at a stalemate, Moscow has used missiles and drones to attack Ukraine’s power equipment, hoping to leave people without electricity as freezing weather sets in.

In a video released by his office from the Bakhmut visit, Zelenskyy was handed a Ukrainian flag and alluded to delivering it to U.S. leaders.

“The guys handed over our beautiful Ukrainian flag with their signatures for us to pass on,” Zelenskyy said in the video. “We are not in an easy situation. The enemy is increasing its army. Our people are braver and need more powerful weapons. We will pass it on from the boys to the Congress, to the president of the United States. We are grateful for their support, but it is not enough. It is a hint — it is not enough.”

For his part, Putin on Tuesday hailed the “courage and self-denial” of his forces in Ukraine — but he did so at a ceremony in an opulent and glittering hall at the Kremlin in Moscow, not on the battlefield.

At the Kremlin ceremony, Putin presented awards to the Moscow-appointed heads of the four illegally annexed regions of Ukraine. In a video address honoring Russia’s military and security agencies, he praised the security personnel deployed to the four regions, saying that “people living there, Russian citizens, count on being protected by you.”

Putin acknowledged the challenges faced by the security personnel.

“Yes, it’s difficult for you,” he said, adding that the situation in the regions is “extremely difficult.”

(AP)